Application of the SAFT equation of state to biomass fast pyrolysis liquid

A practical method has been developed for determining parameters for the statistical associating fluid theory (SAFT) equation of state. Critical temperature, pressure, and density as well as normal boiling point are used to determine parameters for associating compounds, especially sugars. The method has been verified by the description of sugar solubilities in water and in mixed solvents. The predicted and correlated results are in good agreement with the experimental data of systems containing D-fructose, D-glucose, and sucrose. The SAFT model has been further applied to a sugar-containing system in modeling of the recovery of chemicals, such as the sugars levoglucosan and hydroxyacetaldehyde, from a pyrolysis liquid produced from biomass fast pyrolysis. At high temperatures, the two sugars are instable. The modeling of separation of the sugars has been carried out at temperatures 50 °C and 60 °C and in a pressure range of 0.01-0.03 bar. Under these conditions, the effect of pressure on the separation is larger than that of temperature. A lower pressure and a higher water content of the pyrolysis liquid are favourable for the separation. With pressure decreasing, the effect of water content on the separation is becoming less significant.